… a regression that could cause a memory leak if query cache was used together with InnoDB. Bug fixed #1170103. Fixed the… fix for bug #710799. This regression caused mysql schema to be missing after the clean RPM installation. Bug fixed #1174426. Fixed the… #1171941. Fixed the CVE-2012-5627 vulnerability, where an unprivileged MySQL account owner could perform brute-force password guessing attack on…
Post: Virident vCache vs. FlashCache: Part 1
May 16, 2013 By 3 Comments
… to conduct some benchmarks for the use case where the MySQL working set is significantly larger than the InnoDB buffer pool… “1″ to the do_sync sysctl of the cache device triggers a cache flush, but it happens in the background, and while… as the time period before “idle” dirty blocks are cleaned from the cache device. It is not entirely clear whether or not…
Post: Implications of Metadata Locking Changes in MySQL 5.5
February 1, 2013 By 9 Comments
… Locking behavior prior to MySQL 5.5.3 Metadata Locking behavior prior to MySQL 5.5.3 Prior to MySQL 5.5.3… privileges on cached | 0.000003 | | checking permissions | 0.000005 | | sending cached result to clien | 0.000011 | | logging slow query | 0.000002 | | cleaning up… operation waiting, will block. Why? Because MySQL sees that the old entries in the Table Cache have to be invalidated, and any…
Post: Query Profiling with MySQL: Bypassing caches
September 12, 2007 By 6 Comments
… simple – because SQL_NO_CACHE only bypasses query cache but it has no change on other caches, which are MySQL Caches – Innodb Buffer Pool and… caches? For MySQL Caches you can restart MySQL and this is the only way to clean all of the caches. You can do FLUSH TABLES to clean MySQL table cache…
Post: Write contentions on the query cache
September 5, 2012 By 5 Comments
…000032 | | freeing items | 0.000035 | | logging slow query | 0.000004 | | cleaning up | 0.000005 | +———————-+———-+ So the unstable response times did … why did MySQL need so many accesses to the query cache lock? The answer is in the way the query cache works. …
Post: Getting real life query speeds with MySQL
January 10, 2007 By 10 Comments
… kind of other caches and QueryCache is only first in line. There is also all kinds of page caches inside MySQL (key_buffer and innodb_buffer_pool_size) which can be cleared by MySQL restart. Even if you restart MySQL server… makes sense. In this case you would want to clean MySQL and OS caches, most simple way being to restart OS (there are…
Post: Troubleshooting MySQL Memory Usage
March 21, 2012 By 5 Comments
… Check for Table Cache Related Allocations There are cases when MySQL will allocate a lot of memory for table cache, especially if you…) are all connection buffers and so if you close connection MySQL can clean them up. Killing connections (or stopping related applications) and… and fixed. This is where your MySQL Support contract can be handy. Conclusion Understanding where MySQL can allocate memory can help us…
Post: Aligning IO on a hard disk RAID – the Benchmarks
June 9, 2011 By 13 Comments
… make sure caches were clean. OLTP benchmark As the goal was to compare performance with different IO alignment, not different MySQL configurations, I didn’t try out different MySQL versions or settings. Moreover, I have…
Post: Caching techinques
August 8, 2006 By 11 Comments
…. Cache Invalidate With this apporach you invalidate or remove objects in cache once underlying information is updated. This is how MySQL Query Cache works… of what has to be invalidated – approach used by MySQL Query Cache is too coarse invalidating a lot of queries which really… this approach is – you cache operations have constant complexity – you do not have to do big invalidation clean up on updates. Let…
Post: MySQL Crash Recovery
July 30, 2006 By 30 Comments
… only problem as we’ll see. MySQL has angel process mysqld_safe which will restart MySQL Server in most cases. It is… unsync with internal Innodb dictionary may cause MySQL to fail with wierd error messages. In MySQL 4.1 sync_frm option was… – If you restart MySQL server its caches (key_buffer, innodb_buffer_pool, query_cache,table_cache) are cleaned, so may be OS caches. This may reduce…
